The present invention relates generally to the field of medical catheters. In particular it relates to a catheter for providing access to a blood vessel and the like and having features which facilitate its introduction into the vessel.
Winged infusion sets are commonly used by the medical profession for the infusion of medication and the drawing of fluids from vessels. A species of such devices (a "scalp vein set") may comprise a needle with wings attached to it. Attached to the needle, and in fluid communication with the needle bore is a translucent tube through which medication can be infused or fluids drawn. Another species (a winged catheter introducer), comprises a flexible cannula attached to a winged member and a translucent tube. Inside the cannula is a needle with a wire attached to it. The needle aids in the insertion of the catheter into a vessel and is withdrawn by pulling the wire once the cannula has been successfully introduced into the vessel.
Such devices are introduced into the vessel as follows: The wings are gripped between the practitioner's forefinger and thumb. The practitioner uses the needle to pierce the skin in the vicinity of the vessel to be accessed. When the vessel is penetrated, the pressure in the vessel will cause blood to flow up the needle bore and into the translucent tubing. The practitioner verifies the penetration of the vessel by looking for blood "flashback" in the tubing. Once the device is satisfactorily positioned in the vessel it may be left there for some time. In the case of a winged catheter introducer, the needle is withdrawn from the cannula.
A device of the second species is shown in U.S. Pat. Nos. 4,177,809 and 5,163,913, which are incorporated herein by reference. Such devices are sold under the trademarks Intima.TM. and Angioset.RTM. by Becton Dickinson & Co. of Franklin Lakes, N.J.
The gripping of the needle to facilitate insertion of the cannula is accomplished by the use of wedges on the wings which impinge on the plastic sheath surrounding the needle when the wings are brought towards each other. The needle is gripped by the inner surface of the sheath which is distorted by the wedges. This structure requires that the wings be brought towards each other in the right direction or the needle will not be gripped. Using devices of the prior art, practitioners and nurses tend to bring the wings towards each other in the wrong direction. There is therefore a need to provide an incentive to practitioners and nurses to bring the wings towards each other in the right direction to ensure that the needle is gripped properly.